Telephone receiver



March 23 1926.

P. G. ANDRES TELEPHONE RECEIVER Filed May 8. 1922 @Lim *I1-menvr- Paul E flndres Paterad Mar. ze., 1926.

' UNITED STATES,-

PATENT OFFICE.

PAUL G. ANDRES., OF RIVER FOREST, ILLINOIS, ASSIGNOIQ BY IMIESNIIASSIGNMENTS,

p T AUTOMATIC ELECTRIC,- INC., OF CHICAGO, ILLINOIS, A. CORPORATICN OF DELA- p WARE.

Application filed may To all whom t *may concern.' l

Be it known that I, PAUL G. ANDRES, a citizen ofi the United States of America, and a resident of River Forest, Cook County,

- .and State of Illinois,lhave invented certain new and useful Improvements in Telephone Receivers, of which the following is a specification.

My invention relates in general to tele` phone receivers and particularly to an improved magnetic-construction therefor.

Among the objects o'f-the invention are:

to provide a novel magnetic construction of a receiver having a leakage or shunt path of low reluctance for themagneticfluX gener- 'ated by voice currents in the coil thereof; to

. 'provide a single center .coil receiver of high efficiency; to .provide a 1permanent magnet recelver in which the permanent magnet will ary in the ordinary type of radio receiving apparatus to use a polarized receiver in a circuit with -the audion bulb detector in which a certain lamount of direct current flows through the coil of the receiver. In

the usual type of 2 coil polarized receiver the direct current may flow through the windings so as to oppose or aid the magnetic field produced 'by the permanent magnet. If both coils are not wound to exactly the same number of turns the coil with the greater number of turnswill exerta greater I pull on the diaphragm. This causes the diaphragm to be distorted. and consequently when the -winding is further energized with .5 alternating current the diaphragm will not 'l vibrate as a unit with the greatest deflection at the center.

` 'In the receiver of new design however it does not matter Whether it be poled sothat .5 the direct current aids or opposes the permanent magnet liuX as the diaphragm wi-ll A`always be deiected greatestatA the center and when alternating current` impressed the diaphragm is deected as a 'unit since the TELEPHONE lu'iiciilvnl..v y

1922. serial 110.559,378.

pull 4comes at the exact center of the diaphragm. This results in the receiver'talking clear and crisp.

A further advantage results in having a l path for the alternating current iiux, which- `may flow without causing demagnetization of the permanent magnet.

Referring to the drawings, I have shown in Fig. 1 a faceview of a watchcase receiver embodying my invention.

Fig. 2 is a sectional view of the receiver shown in Fig. 1 looking in the direction of the arrows along the line A`A.

Fig. 3 is a diagrammatical illustration of the magnetic principles of the invention.

Fig. 4 is a diagrammatical illustration of a modification ofthe magnetic circuit of Fig. 3. i

Fig. 5 also shows a slight modification of the magnetic circuit. l

Fig. 6 shows kan ordinary polarized telephone receiver embod in my invention.

I will nowdescribe 1n etail the principles and construction -of the receiver of my invention by referring to the above described drawings. l

The receiver of Figs. l 'and 2 consists of a horseshoe permanent magnet 2 comprising twoseparate sectionsmounted in the usual aluminum, bakelite, or rubber casing 3 by means of screws 4. 'A pair of threaded soft iron sleeves 5 are held clamped against the opposite ends of the magnet 2 by screws 4. Under .one pole of the magnet 2 and held clamped against the back of the casing 3 is a soft iron part 6l which forms an extension'I of one pole of magnet 2. This part'6 carries a stud in the cente'r of the receiver which` forms the core of a coil 7 having insulating washers 8 thereon to hold the winding of. the coil in place.- A soft iron part 9 is placed under the pole of the magnet 2 opposite the part 6 to space'the magnet equally with re1a tion to the casing, the part 9 being equal in thickness totheelement 6.;

A block of insulating materiallO is mount-A ed on the casing 3 by means Q fa brass screw 11 between the poles of the et 2 to serve asy a terminal block. This b-woek 10 carries a pair of screws 12 which lcath hold' a terof the usual receiver cablev may be connected minal ofthe coil 7 and to which the ends as shown in Fig. 1.

Ageiaphmgm 13 of the usual'type is heid.

' by means of a cap 14 of insulating material which isthreaded upon the rim`of the casing 3.-

The receiver above described is of very simple construction, and consists of few parts, the coil 7 being wound on the iron piece 6 as a unit. The permanent magnets have a leakage path for the flux passing through the extending arm 6 as well as through the diaphragm.

Referring now to Fig. 3 it will be seen that when the coil 7 is energized the magnetic lux generated in the core has a local path including the core of coil, the part 6',

the left hand pole/piece 5', and the diaphragm, thus the flux in the coil 7does not affect the magnetism of the permane it magnet as it would if the flux were reqiiired to pass therethrough. The variations in flux caused by voice currents will follow the above described shunt path, this path being of far less reluctance than the path usually followed through the permanentJ magnets or through an air gap.

This magnetic structure consists of a .permanent magnet having a split pole as illustrated in Fig. 3 there being two north poles and one south pole as indicated. The poles being all of soft iron it will follow that all variations of .the flux generated in the coil 7 vwill cause the magnetic iluX passing through the two north poles to shift and the flux through lone north pole will decrease while the iux through the other northpole will increase. In other words all variations of flux will take place only in the series path, including the twobranches of the north pole of the magnet, and the diaphragm, which path is of very low reluctance and therefore tends to highest receiving efliciency.

Fig. 4 is a diagrammatic showing of a modifiedmagnetic circuit of thesame general plan as that shown in Fig. 3, except that the shunt path is made shorter; in other wo'rds, the two poles 5 of soft iron may be brought nearer toy the center of the diaphragm if desired, and may in this case be of smaller size. i

Another soft iron sleeve may be included l in this magnetic circuit as shown in Fig. 5

of the drawings at 15, thus tending to dis tribute the,permanent magnet pull on the diaphragm and also to pr'ovide an additional shunt path for the variations of magnetic force.

It will be readily seen that this magnetic construction may as easily he applied vto the ordinary type of telephone receiver as shown in Fig. 6 of the drawings in which case the usual type of shell and cap will be employed with a permanent magnetl of standard type, the poles of the magnet will be of soft iron -as described in connection with the otherl figures of the drawings and the coll 16 will be wound on a center pole with a shunt path for variations of flux through the cross arm 17 and the soft iron pole 18.

Having fully described and ascertained `the features and aspects of my invention what I consider to be new and desire to have pro, tected by Letters P atent will be set forth in the appended claims.

What I claim as my invention is:

1. In a telephone receiver, a diaphragm, a permanent magnet having two soft iron pole piece extensions adjacent the diaphragm and a branch from one .of said extensions also adjacent the diaphragm at the geometrical center thereof, and means for producing variations in the magnetic flux in the branch and extension otwhich it is a part to influence the diaphragm.

2. In a telephone receiver, a diaphragm, a permanent magnet having soft iron pole pieces, a branch of one of said soft iron poles located at the geometrical center of said diaphragm and having a coil wound thereon for producing variations in the magnetic flux in said branch, and a path of .low reluctance for said Variations in flux including only the soft iron pole of which it is a branch and the diaphragm.

3. In a telephone receiver, a diaphragm, a permanent magnet having two like poles and only one opposite pole adjacent said diaphragm, means for producing variations in iuX in one of the two like poles, and a low reluctance path for said variations in flux excluding the permanent magnet.

4. Inv a telephone receiver, a diaphragm, a permanent magnet having two like poles and only one opposite pole adjacent said diaphragm, means for producing yvariations in iuX in one of the two like poles, and a low reluctance path for said variations in iux excluding the permanent magnet, a diaphragm mounted adjacent said magnet and infiuenced by the variations in iiuX in said like poles. y

5. In a telephone receiver, a diaphragm, :soft iron pole pieces, a permanent magnet for maintaining an initial magnetic stress on saiddiaphragm through said pole pieces, said magnet having two poles of like polarity and only one of opposite polarity adjacent the diaphragm, a path for the magnetic flux of said magnet including the two like poles in parallel, the diaphragm and "the magnet, and means for shifting the magnetic flux from one of said parallel paths to the other to influence the diaphragm,said means acting over a magnetic path which contains only soft i-ron. 6. In a telephone receiver, a diaphragm, a permanent magnet, a pair of soft irc-:1

poles therefor, another soft iron pole at- Wound on said other'pole piece for producing variations in the flux therein, and a path of low reluctance for said variations of flux consisting of only ,the center pole, the'diaphragm and the pole to which the center pole is attached,

7. In a 'telephone receiver, a diaphragm, a permanent magnet having pole pieces disposed around they edges of said diaphragm,

lanother pole piece' attached to said magnetand extending under the geomet'rical'center of said diaphragm `and having'an alternat ing current coil wound thereon for producing variationsof magnetic flux' therein, and a path of low reluctance'for said variations off-lux in th'e `centcrpole excluding said permanent magnet.

8. In a telephone receiver, a permanent magnet, two soft iron pole p1eces therefor,

said poles being located beneath said'dia'l phragm and near the circumference, a soft' iron core located beneath the geometrical center of said diaphragm and attached tol oneof said poles, a coil on said core, the

core and pole formina soft iron'magnetic like polarity and one of opposite polarity,

a coil on one of said like poles, said coil vand pole being locatedat the geometrical center of the diaphragm, Athe other like pole and the opposite pole being located near the circumference of said diaphragm, a soft iron path for the flux set up by said coil including onlysaid like poles and diaphragm.

`l'nvvtitnesswhereof, I hereunto subscribe my name this 1st day of May, A, D., 1922.

PAUL G. ANDRES 

